1. Field of the Invention
The present invention relates to a method and an apparatus of generating a carbon nanotube (CNT). More particularly, the present invention relates to a method and an apparatus of generating a CNT by use of a catalyst powder.
2. Description of the Related Art
Carbon nanotubes (CNTs) are allotropes of carbon with a nanostructure in which carbon atoms are combined with one another in a hexagonal structure, similar to a beehive, into a cylindrical tube of which the diameter is in the order of a few nanometers. Since the CNTs have excellent mechanical properties, superior field-emission characteristics and electrical selectivity, and highly efficient hydrogen storage properties, the CNTs are widely employed in many technical fields such as aeronautical and space engineering, biological engineering, environmental energy, materials industry, medicine, computers and security and safety, etc.
In general, conventional CNTs are generated by one of an electric discharge process, a plasma chemical vapor deposition (CVD) process, a thermal CVD process and a thermal decomposition process. Particularly, the thermal CVD process and the thermal decomposition process have been most widely used to generate the CNTs.
FIG. 1 is a cross-sectional view illustrating a schematic structure of an apparatus for generating conventional CNTs.
Referring to FIG. 1, the conventional CNTs are generated by a thermal CVD process or a thermal decomposition process in the apparatus including a cylindrical process chamber 1 of which the central axis is arranged in a horizontal direction and a heater 3 enclosing the process chamber 1. The process chamber 1 is heated to a temperature of about 600° C. to about 1,100° C. by the heater 3.
Source gases are supplied into a first end portion of the process chamber 1 and are discharged out of the process chamber 1 from a second end portion of the process chamber 1 opposite to the first end portion. A substrate (not shown) is loaded into the process chamber 1 and the process chamber 1 is heated to a high temperature. The source gases are supplied into the high-temperature process chamber 1, and the CNTs are generated on the substrate in the process chamber 1.
However, the process chamber 1 is partially enclosed by the heater in the conventional apparatus, because the heat generated from the heater 3 may have undesired effects on other elements of the apparatus around the process chamber 1 when the whole surface of the process chamber 1 is enclosed by the heater 3. For that reason, the substrate is positioned only in a portion of the process chamber that is sufficiently enclosed by the heater 3, which reduces the space efficiency of the process chamber 1. Further, the reduction of the space efficiency of the process chamber 1 may prevent larger apparatuses from being used.
In addition, the process chamber 1 is directly heated by the heater 3, and thus the life span of the process chamber 1 may be significantly shortened.